1. Field of the Invention
The present invention relates to a semiconductor device and method of making the same, and more particularly, to a method of forming semiconductor device that uses a non-implant process to form a semiconductor device with low resistant doped layers.
2. Description of the Prior Art
Compared with amorphous silicon thin film transistor device, polycrystalline silicon thin film transistor device exhibits superior electrical property due to its high electrical mobility. As low temp polycrystalline silicon (LTPS) process advances, some major issue, e.g. poor uniformity of large-size film, has been improved. Thus, LTPS process has been expected to be applied in large-size display panel fabrication. The conventional LTPS process, nevertheless, normally uses an ion implant process to form doped layers for reducing the contact resistance in the thin film transistor device. To introduce the ion implant apparatus into large-size display panel fabrication would result in many technique problems and high cost. Therefore, to seek an alternative method for forming low resistant doped layers has become one of the developing goals.
In addition, LTPS thin film transistor device may be N type thin film transistor device or P type thin film transistor device when different conductive types of doped layers are used. In the conventional LTPS process, when both N type thin film transistor device and P type thin film transistor device are required, a patterned N type doped semiconductor layer and a patterned P type doped semiconductor layer are formed respectively on the same substrate, which would cause damages to the polycrystalline layer. For example, if the N type doped semiconductor layer is formed subsequent to the P type doped semiconductor layer, the polycrystalline silicon layer of the N type thin film transistor device will be damaged twice by two etching processes. Accordingly, the device characteristic of the N type thin film transistor device will be deteriorated.